Download AN569

AN569
AM/SW tuner test equipment lists:
Rohde
& Schwarz UPL Audio Analyzer
&Schwarz SML01 Signal Generator
Mini-Circuits Power Combiner
SW Antenna Dummy
Rohde
Figure 8. SW Antenna Dummy Circuit
4.2. AM/SW Tuner Testing Considerations
Several issues must be considered to make accurate measurements.
First, the power combiner and cable losses must be calibrated and factored into each measurement. The loss for
the Mini-Circuit power combiner is approximately 6 dB.
Second, most signal generators display the voltage generated at the input of the device under test (DUT) assuming
an input resistance of 50 Ω. For example, if the signal generator displays VL = 1 μV (0 dBμV), the generator source
voltage VS is 2 μV (6 dBμV). The load voltage VL is generated from the source voltage VS by the voltage divider
created by the 50  generator source resistance RS and the 50  load resistance RL. This distinction is important
only for sensitivity, RDS sensitivity, and IP3, which are specified in μV EMF*, where EMF refers to the source
voltage VS. Measurements such as AM suppression, selectivity, and spurious response are relative and may be
referenced using VS or VL. To summarize, the generator displays the voltage at the input of the DUT. With the
Si4831/35/20/24 AM/SW tuner, the input impedance is high, so the voltage needs to be doubled (add 6 dB) to
convert the value displayed on the signal generator to EMF.
For SW testing, connect the SG to the antenna input through an antenna dummy to simulate the characteristics of
normal whip antenna at SW frequency band.
Rev. 0.2
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